Compilare: user.cpp: In function ‘void read()’: user.cpp:20:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d %d", &N, &M); ^ user.cpp:24:59: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i = 1; i <= length; i++) fscanf(in, "%lld", &v[i]); ^ user.cpp: In function ‘void query()’: user.cpp:60:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &Q); ^ user.cpp:64:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%lld", &x); ^